Using dynamic bursts to support frequency-agile memory interfaces

Abstract

The disclosed embodiments relate to a system that supports dynamic bursts to facilitate frequency-agile communication between a memory controller and a memory device. During operation, the system monitors a reference clock signal received at an interface between the memory device and the memory controller. Upon detecting a frequency change in the reference clock signal from a fullrate to a subrate, the interface operates in a burst mode, wherein data is communicated through bursts separated by intervening low-power intervals during which portions of the interface are powered down.

What is claimed is: 
     
       1. A method, comprising:
 in response to detecting a decrease in a first data rate of a first interface of a memory controller, operating a second interface of the memory controller in burst mode by alternating the second interface between a power-on state and a power-off state. 
 
     
     
       2. The method of  claim 1 , wherein said alternating the second interface between the power-on state and the power-off state comprises:
 switching the second interface of the memory controller from the power-off state to the power-on state when a first counter reaches a first pre-specified value; and 
 switching the second interface of the memory controller from the power-on state to the power-off state when a second counter reaches a second pre-specified value. 
 
     
     
       3. The method of  claim 1 , wherein said alternating the second interface between the power-on state and the power-off state comprises:
 switching the second interface of the memory controller from the power-off state to the power-on state when a first first-in first-out (FIFO) pointer reaches a first pre-specified trip point; and 
 switching the second interface of the memory controller from the power-on state to the power-off state when a second FIFO pointer reaches a second pre-specified trip point. 
 
     
     
       4. The method of  claim 1 , wherein, in the power-on state, the second interface operates at a second data rate that is greater than the first data rate, and wherein, in the power-off state, the second interface is turned off. 
     
     
       5. The method of  claim 4 , wherein an average data rate of the second interface matches the first data rate. 
     
     
       6. The method of  claim 4 , wherein the second data rate is an integral multiple of the first data rate. 
     
     
       7. The method of  claim 1 , wherein the method comprises:
 operating the first interface by using a first clock signal; 
 generating a second clock signal from the first clock signal by using a Multiplying Injection Locked Oscillator (MILO); and 
 operating the second interface by using the second clock signal. 
 
     
     
       8. The method of  claim 1 , comprising:
 in response to detecting an increase in the first data rate of the first interface of the memory controller, ceasing to operate the second interface of the memory controller in burst mode. 
 
     
     
       9. An integrated circuit, comprising:
 a first interface communicatively coupled to a processer; 
 a second interface communicatively coupled to a memory device; and 
 a control circuit to operate the second interface in burst mode in response to detecting a decrease in a first data rate of the first interface, wherein the burst mode comprises alternating the second interface between a power-on state and a power-off state. 
 
     
     
       10. The integrated circuit of  claim 9 , wherein said alternating the second interface between the power-on state and the power-off state comprises:
 switching the second interface from the power-off state to the power-on state when a first counter reaches a first pre-specified value; and 
 switching the second interface from the power-on state to the power-off state when a second counter reaches a second pre-specified value. 
 
     
     
       11. The integrated circuit of  claim 9 , wherein said alternating the second interface between the power-on state and the power-off state comprises:
 switching the second interface of from the power-off state to the power-on state when a first first-in first-out (FIFO) pointer reaches a first pre-specified trip point; and 
 switching the second interface from the power-on state to the power-off state when a second FIFO pointer reaches a second pre-specified trip point. 
 
     
     
       12. The integrated circuit of  claim 9 , wherein, in the power-on state, the second interface operates at a second data rate that is greater than the first data rate, and wherein, in the power-off state, the second interface is turned off. 
     
     
       13. The integrated circuit of  claim 12 , wherein an average data rate of the second interface matches the first data rate. 
     
     
       14. The integrated circuit of  claim 12 , wherein the second data rate is an integral multiple of the first data rate. 
     
     
       15. The integrated circuit of  claim 9 , comprising:
 a Multiplying Injection Locked Oscillator (MILO) to generate a second clock signal from a first clock signal; 
 wherein the first interface operates based on the first clock signal; and 
 wherein the second interface operates based on the second clock signal. 
 
     
     
       16. The integrated circuit of  claim 9 , wherein the control circuit ceases to operate the second interface in the burst mode in response to detecting an increase in the first data rate of the first interface. 
     
     
       17. A system, comprising:
 a processor coupled to a first interface of a memory controller; 
 a memory device coupled to a second interface of the memory controller; and 
 the memory controller comprising a control circuit to operate the second interface in burst mode in response to detecting a decrease in a first data rate of the first interface, wherein the burst mode comprises alternating the second interface between a power-on state and a power-off state.